The Volcker Rule was implemented to restrict United States banks from engaging in certain speculative investments that do not benefit customers of the bank. The rule is sometimes referred to as a ban on proprietary trading (also known as “prop trade”) by commercial banks and the use of deposits to trade on the bank's own accounts (e.g., the bank cannot take its own money and invest/trade with that money). A derivative is a contract that derives its value form the performance of the underlying entity. In the case of derivatives, it may be difficult to monitor the status of prop trades and, therefore, it may be difficult to effectively monitor conformance with the Volcker Rule for trading desks that primarily deal with derivatives.